Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/004—Photosensitive materials
  • G03F7/027—Non-macromolecular photopolymerisable compounds having carbon-to-carbon double bonds, e.g. ethylenic compounds
  • G03F7/028—Non-macromolecular photopolymerisable compounds having carbon-to-carbon double bonds, e.g. ethylenic compounds with photosensitivity-increasing substances, e.g. photoinitiators
  • G03F7/031—Organic compounds not covered by group G03F7/029

Definitions

• the present invention relates to a photosensitive lithographic printing plate.
• the invention relates to a photosensitive printing plate which is suitable for image drawing by laser light and which is suitable for high definition AM screen printing with the number of screen lines of 200 lines or more or FM screen printing.
• a desired printing plate was obtained by using a lithographic printing plate having a construction comprising a support having a hydrophilic surface and having a photosensitive resin layer provided thereon and by usually employing a plate-making method by subjecting the lithographic printing plate to surface exposure (mask exposure) via a lith film and then removing a non-image area by a developing solution.
• a computer-to-plate (CTP) technology for performing exposure directly on a plate surface without using a lith film by scanning light with high directivity such as laser light according to digitalized image information has been developed, and photosensitive lithographic printing plates adaptive thereto have also been developed.
• a photosensitive printing plate which is suitable for exposure with laser light
• a photosensitive lithographic printing plate using a polymerizable photosensitive layer.
• the polymerizable photosensitive layer makes it easy to realize high sensitivity by choosing a polymerization initiator or polymerization initiation system (hereinafter sometimes referred to simply as “initiator” or “initiation system”) as compared with other conventional photosensitive layers.
• the FM (frequency modulation) screen as referred to herein is one in which fine halftone dots of approximately 20 microns are aligned at random regardless of a screen angle or the number of screen lines and a density gradation is expressed by a density of halftone dots per unit area.
• Printed matters by this FM screen printing are characterized in that an interference moiré or Rosseta pattern is not generated; that tone jump is not generated in a half tone portion in the vicinity of 50 %; and that since the halftone dots are small, halftone dots scarcely overlap each other so that reproduced colors are vividly seen.
• the AM (amplitude modulation) screen is meant by one in which halftone dots are regularly aligned at a certain angle and the density gradation is expressed by the size of halftone dots per unit area.
• the number of screen lines of the AM screen is 175 lines per inch.
• the high definition screen is meant by one using the number of screen lines of 200 lines or more.
• High definition printed matters are characterized by a reduction of a moiré or Rosseta pattern, an enhancement of a texture of the image, and enhancements of a sense of reality and reproducibility of fine portions.
• JP-A-2003-43703 discloses a photosensitive lithographic printing plate comprising a support having thereon an interlayer containing a high-molecular compound having a constituent unit having a sulfonic group in the side chain thereof and a polymerizable photosensitive layer in this order.
• this photosensitive lithographic printing plate is not sufficient yet as a plate material suitable for high definition AM screen or FM screen printing.
• unevenness in flat tint is vigorous in the FM screen so that it was difficult to use the FM screen.
• An object of the invention is to provide a photopolymerization type photosensitive lithographic printing plate which is suitable for image drawing by laser light and which has good uniformity of unevenness in flat tint of a half tone by high definition AM screen printing with the number of screen lines of 200 lines or more or FM screen printing, especially FM screen printing.
• the present inventors made extensive and intensive investigations. As a result, it has been found that in a circumstance where sensitivity and high definition are in the trade-off relation, by blending a sensitizing dye such that an OD value of the photosensitive layer in the exposure wavelength becomes small, it is possible to make the both sensitivity and high definition compatible with each other, leading to accomplishment of the invention.
• the invention is as follows.
• a photopolymerization type photosensitive lithographic printing plate which is suitable for image drawing by laser light and which has good uniformity of unevenness in flat tint of a half tone by high definition AM screen printing with the number of screen lines of 200 lines or more or FM screen printing, especially FM screen printing.
• a photosensitive lithographic printing plate (lithographic printing plate precursor) having spectral sensitivity in a wavelength region of from 360 nm to 450 nm, which is used in the invention, its construction will be successively described below.
• any material is useful so far as its surface is hydrophilic, a dimensionally stable plate-like material is preferable.
• a plastic for example, polyethylene, polypropylene, and polystyrene
• plates of a metal for example, aluminum (inclusive of aluminum alloys) , zinc, and copper
• an alloy thereof for example, alloys with silicon, copper, manganese, magnesium, chromium, zinc, lead, bismuth, nickel, etc.
• films of a plastic for example, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, and polyvinyl acetate
• papers or plastic films laminated or vapor deposited with the foregoing metal or metal alloy for example, papers, papers laminated with a plastic (for example, polyethylene, polypropylene, and polystyrene), plates
• the support is subjected to surface treatment such as graining treatment, dip treatment in an aqueous solution of sodium silicate, potassium fluorozirconate, a phosphate, etc., and anodic oxidation treatment as described later.
• surface treatment such as graining treatment, dip treatment in an aqueous solution of sodium silicate, potassium fluorozirconate, a phosphate, etc., and anodic oxidation treatment as described later.
• Examples of the graining treatment include mechanical graining, chemical etching, and electrolytic graining as disclosed in JP-A-56-28893.
• an electrochemical graining method for performing electrochemical graining in a hydrochloric acid or nitric acid electrolytic liquid and a mechanical graining method such as a wire brush graining method for scratching the aluminum surface by a metallic wire, a ball graining method for graining the aluminum surface by an abrasive ball and an abrasive material, and a brush graining method for graining the surface by a nylon brush and an abrasive material are employable.
• the foregoing graining methods can be carried out singly or in combination.
• a method for preparing a surface roughness to be usefully employed in the invention is an electrochemical method for performing chemical graining in a hydrochloric acid or nitric acid electrolytic liquid, and a suitable current density is in the range of from 100 C/dm 2 to 400 C/dm 2 . More specifically, it is preferable that the electrolysis is carried out in an electrolytic liquid containing from 0.1 to 50 % of hydrochloric acid or nitric acid under conditions at a temperature of from 20 to 100 °C for a period of time of from 1 second to 30 minutes and at a current density of from 100 C/dm 2 to 400 C/dm 2 .
• the thus grained aluminum support is chemically etched with an acid or alkali.
• an acid as an etchant
• an alkali as an etchant
• alkaline agent which can be suitably used in the invention include sodium hydroxide, sodium carbonate, sodium aluminate, sodium metasilicate, sodium phosphate, potassium hydroxide, and lithium hydroxide.
• Preferred ranges of the concentration and temperature are from 1 to 50 % and from 20 to 100 °C, respectively.
• the amount of dissolution of aluminum is preferably from 5 to 20 g/m 3 .
• acid washing is carried out.
• the acid to be used include nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, and borofluoric acid.
• a method for bringing it into contact with sulfuric acid of from 15 to 65 % by weight at a temperature of from 50 to 90 °C as described in JP-A-53-12739 and an alkaline etching method as described in JP-B-48-28123 are preferable.
• a preferred surface roughness (Ra) of the aluminum support is from 0.3 to 0.7 ⁇ m.
• the thus treated aluminum support is further subjected to anodic oxidation treatment.
• the anodic oxidation treatment can be carried out by a method which has hitherto been employed in this technical field.
• anodically oxidized film on the surface of the aluminum support by passing a direct current or alternating current through aluminum in an aqueous solution or non-aqueous solution of sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, etc. or a combination of two or more kinds thereof.
• the conditions of the anodic oxidation treatment vary in all sorts of ways depending upon an electrolytic liquid to be used and therefore, cannot be unequivocally determined. However, in general, it is suitable that the concentration of the electrolytic liquid ranges from 1 to 80 %; the liquid temperature ranges from 5 to 70 °C; the current density ranges from 0.5 to 60 A/dm 2 ; the voltage ranges from 1 to 100 V; and the electrolysis time ranges from 10 to 100 seconds.
• the anodically oxidized film is preferably from 1 to 10 g/m 2 , more preferably from 1.5 to 7 g/m 2 , and further preferably from 2 to 5 g/m 2 .
• the support may be subjected to sealing treatment after the graining treatment and anodic oxidation treatment.
• the sealing treatment is carried out by dipping the substrate in a hot aqueous solution containing hot water and an inorganic salt or organic salt, a steam bath, or the like.
• the support which is used in the invention may be subjected to surface treatment other than silicate treatment with an alkali metal silicate, such as dipping treatment in an aqueous solution of potassium fluorozirconate, a phosphate, etc.
• a photosensitive lithographic printing plate is formed by, for example, applying a polymerizable photosensitive layer composed of a photosensitive composition on the support (in the case of aluminum, aluminum having been subjected to appropriate surface treatment as described previously is preferable) and subsequently applying a protective layer.
• a polymerizable photosensitive layer composed of a photosensitive composition on the support (in the case of aluminum, aluminum having been subjected to appropriate surface treatment as described previously is preferable) and subsequently applying a protective layer.
• an organic or inorganic undercoat layer may be provided prior to the application of a polymerizable photosensitive layer, or the support may be subjected to sol-gel treatment having a functional group capable of causing addition reaction by a radical covalent bonded thereto as disclosed in JP-A-7-159983.
• Examples of a substance which forms the organic undercoat layer include water-soluble resins (for example, polyvinylphosphonic acid, polymers or copolymers having a sulfonic group in the side chain thereof, and polyacrylic acid) , water-soluble metal salts (for example, zinc borate), yellow dyes, and amine salts.
• water-soluble resins for example, polyvinylphosphonic acid, polymers or copolymers having a sulfonic group in the side chain thereof, and polyacrylic acid
• water-soluble metal salts for example, zinc borate
• yellow dyes for example, yellow dyes, and amine salts.
• examples of an organic compound which is used in the organic undercoat layer include carboxymethyl cellulose, dextrin, gum arabic, amino group-containing phosphonic acids (for example, 2-aminoethylphosphonic acid), organic phosphonic acids (for example, phenylphosphonic acid, naphthylphosphonic acid, alkylphosphonic acids, glycerophosphonic acid, methylenediphosphonic acid, and ethylenediphosphonic acid, each of which may have a substituent), organic phosphoric acids (for example, phenylphosphoric acid, naphthylphosphoric acid, alkylphosphoric acids, and glycerophosphoric acid, each of which may have a substituent), organic phosphinic acids (for example, phenylphosphinic acid, naphthylphosphinic acid, alkylphosphinic acids, and glycerophosphinic acid, each of which may have a substituent), amino acids (for example, glycine and ⁇
• This organic undercoat layer can be provided by the following method. That is, examples of the method include a method in which a solution having the foregoing organic compound dissolved in water or an organic solvent (for example, methanol, ethanol, and methyl ethyl ketone) or a mixed solvent thereof is coated on a support and then dried to provide an organic undercoat layer; and a method in which a support is dipped in a solution having the foregoing organic compound dissolved in water or an organic solvent (for example, methanol, ethanol, and methyl ethyl ketone) or a mixed solvent thereof to adsorb the foregoing organic compound thereon and then washed with water, etc. and dried to provide an organic undercoat layer.
• an organic solvent for example, methanol, ethanol, and methyl ethyl ketone
• a solution of the foregoing organic compound having a concentration of from 0.005 to 10 % by weight can be coated by a variety of methods.
• any of methods including bar coater coating, rotary coating, spray coating, and curtain coating may be employed.
• the concentration of the solution is from 0.01 to 20 % by weight, and preferably from 0.05 to 5 % by weight;
• the dipping temperature is from 20 to 90 °C, and preferably from 25 to 50 °C ; and the dipping time is from 0.1 seconds to 20 minutes, and preferably from 2 seconds to one minute.
• the solution which is used therefor is adjusted as to adjust the pH with a basic substance (for example, ammonia, triethylamine, and potassium hydroxide) or an acidic substance (for example, hydrochloric acid and phosphoric acid) , whereby it can be used at a pH in the range of from 1 to 12.
• a basic substance for example, ammonia, triethylamine, and potassium hydroxide
• an acidic substance for example, hydrochloric acid and phosphoric acid
• a yellow dye can also be added.
• the amount of coating of the organic undercoat layer after drying is suitably from 2 to 200 mg/m 2 , and preferably from 5 to 100 mg/m 2 . Within the foregoing range, sufficient printing resistance is obtained.
• examples of a substance which is used in the inorganic undercoat layer include inorganic salts (for example, cobalt acetate, nickel acetate, and potassium fluorotitanate) .
• inorganic salts for example, cobalt acetate, nickel acetate, and potassium fluorotitanate
• a method for providing this inorganic undercoat layer is the same as in the foregoing organic undercoat layer.
• the photosensitive layer of the photosensitive lithographic printing plate which is used in the invention has at least spectral sensitivity in a wavelength region of from 360 nm to 450 nm.
• the photosensitive layer is preferably constructed so as to contain the following components (A) to (D):
• the sensitizing dye which is used in the photosensitive lithographic printing plate to be used in the invention is a sensitizing dye having an absorption maximum in a wavelength region of from 360 nm to 450 nm.
• a sensitizing dye include merocyanine dyes represented by the following formula (2), benzopyrans or coumarins represented by the following formula (3), aromatic ketones represented by the following formula (4), and anthracenes represented by the following formula (5).
• A represents an S atom or NR 6 ;
• R 6 represents a monovalent non-metallic atomic group;
• Y represents a non-metallic atomic group for forming a basic nucleus of dye jointly with the adjacent A and adjacent carbon atom;
• X 1 and X 2 each independently represents a monovalent non-metallic atomic group; and
• X 1 and X 2 may be taken together to form an acidic nucleus of dye.
• Ar 3 represents an optionally substituted aromatic group or heteroaromatic group; and R 13 represents a monovalent non-metallic atomic group. More preferably, R 13 is an aromatic group or a heteroaromatic group; and Ar 3 and R 13 may be taken together to form a ring.
• X 3 , X 4 , and R 14 to R 21 each independently represents a monovalent non-metallic atomic group. More preferably, X 3 and X 4 are each an electron-donating group having a negative Hammett's substituent constant.
• Preferred examples of the monovalent non-metallic atomic group represented by X 1 to X 4 and R 6 to R 21 in the formulae (2) to (5) include a hydrogen atom, an alkyl group (for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a hexadecyl group, an octadecyl group, an eicosyl group, an isopropyl group, an isobutyl group, an s-butyl group, a t-butyl group, an isopentyl group, a neopentyl group, a 1-methylbutyl group, an iso
• Examples of the basic nucleus of dye which Y forms jointly with the adjacent A and adjacent carbon atom in the formula (2) include 5-, 6- or 7-membered nitrogen-containing or sulfur-containing rings. Of these, 5- or 6-membered hetero rings are preferable.
• any of rings which are known to constitute a basic nucleus in merocyanine dyes as described in, for example, L.G. Brooker, et al., J. Am . Chem. Soc., 73, 5326-5358 (1951) and references as cited therein can be suitably used.
• thiazoles for example, thiazole, 4-methylthiazole, 4-phenylthiazole, 5-methylthiazole, 5-phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole, 4,5-di(p-methoxyphenylthiazole), and 4-(2-thienyl) thiazole
• benzothiazoles for example, benzothiazole, 4-chlorobenzothiazole, 5-chlorobenzothiazole, 6-chlorobenzothiazole, 7-chlorobenzothiazole, 4-methylbenzothiazole, 5-methylbenzothiazole, 6-methylbenzothzazole, 5-bromobenzothiazole, 4-phenylbenzothiazole, 5-phenylbenzothiazole, 4-methoxybenzothiazole, 5-methoxybenzothaizole, 6-methoxybenzothiazole, 5-iodobenzothiazole, 6-io
• examples of the sulfur-containing hetero ring include dithiol partial structures in dyes as described in JP-A-3-296759.
• benzodithiols for example, benzodithiol, 5-t-butylbenzodithiol, and 5-methylbenzodithiol
• naphthodithiols for example, naphtho-[1,2]dithiol and naphtho[2,1]dithiol
• dithiols for example, 4,5-dimethyldithiols, 4-phenyldithiols, 4-methoxycarbonyldithiols, 4,5-dimethoxycarbonylbenzodithiols, 4,5-ditrifluoromethyldithiol, 4,5-dicyanodithiol, 4-methoxycarbonylmethyldithiol, and 4-carboxymethyldithiol) .
• hetero ring mother skeletons have been conventionally used for convenience.
• the hetero ring constitutes a basic skeleton partial structure of sensitizing dye, for example, in the case of a benzothiazole skeleton, it is introduced in the form of an alkylidene type substituent in which a degree of unsaturation is decreased by one, as in a 3-substituted-2 (3H) -benzothiazolylidene group.
• a dye represented by the following formula (1) is more preferable from the viewpoint of high sensitivity.
• A represents an optionally substituted aromatic ring or hetero ring
• X represents an oxygen atom, a sulfur atom, or N-(R 3 )
• R 1 , R 2 , and R 3 each independently represents a hydrogen atom or a monovalent non-metallic atomic group
• a and R 1 , or R 2 and R 3 may be bound to each other for forming an aliphatic or aromatic ring.
• R 1 ,R 2 , and R 3 each independently represents a hydrogen atom or a monovalent non-metallic atomic group, and preferably a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aromatic heterocyclic residue, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylthio group, a hydroxyl group, a halogen atom, or a carboxyl group.
• R 1 , R 2 , and R 3 Preferred examples of the alkyl group include linear, branched or cyclic alkyl groups having from 1 to 20 carbon atoms. Specific examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl groups an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a hexadecyl group, an octadecyl group, an eicosyl group, an isopropyl group, an isobutyl group, a sec-butyl group, a t-butyl group, an isopentyl group, a neopentyl group, a 1-methylbutyl group,
• a monovalent non-metallic atomic group other than hydrogen is used as the substituent of the substituted alkyl group.
• Preferred examples thereof include a halogen atom (for example, -F, -Br, -Cl, and -I), a hydroxyl group, an alkoxy group, an aryloxy group, a mercapto group, an alkylthio group, an arylthio group, an alkyldithio group, an aryldithio group, an amino group, an N-alkylamino group, an N,N-dialkylamino group, an N-arylamino group, an N,N-diarylamino group, an N-alkyl-N-arylamino group, an acyloxy group, a carbamoyloxy group, an N-alkylcarbamoyloxy group, an N-arylcarbamoyloxy group, an N,N-dialkylcarbamoyloxy
• N'-alkyl-N'-aryl-N-arylureido group an alkoxycarbonylamino group, an aryloxycarbonylamino group, an N-alkyl-N-alkoxycarbonylamino group, an N-alkyl-N-aryloxycabonylamino group, an N-aryl-N-alkoxycarbonylamino group, an N-aryl-N-aryloxycarbonylamino group, a formyl group, an acyl group, a carboxyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an N-alkylcarbamoyl group, an N,N-dialkylcarbamoyl group, an N-arylcarbamoyl group, an N,N-diarylcarbamoyl group, an N-alkyl-N-arylcarbamoyl group, an alkylsulf
• alkyl group examples include the foregoing alkyl groups; and specific examples of the aryl group include a phenyl group, a biphenyl group, a naphthyl group, a tolyl group, a xylyl group, a mesityl group, a cumenyl group, a chlorophenyl group, a bromophenyl group, a chloromethylphenyl group, a hydroxyphenyl group, a methoxyphenyl group, an ethoxyphenyl group, a phenoxyphenyl group, an acetoxyphenyl group, a benzoyloxyphenyl group, a methylthiophenyl group, a phenylthiophenyl group, a methylaminophenyl group, a dimethylaminophenyl group, an acetylaminophenyl group, a carboxyphenyl group, a meth
• a monocyclic or polycyclic aromatic ring containing at least one of nitrogen, oxygen and sulfur atoms is used.
• the especially preferred heteroaryl group there are enumerated thiophene, thianthrene, furan, pyran, isobenzofuran, chromene, xanthene, phenoxazine, pyrrole, pyrazole, isothiazole, isoxazole, pyrazine, pyrimidine, pyridazine, indolizine, isoindolizine, indoyl, indazole, purine, quinolizine, isoquinoline, phthalazine, naphthylidine, quinazoline, cinoline, pteridine, carbazole, carboline, phenanthrene, acridine, perimidine, phenanthroline, phthalazine, phenar
• alkenyl group as R 1 , R 2 , and R 3 include a vinyl group, a 1-propenyl group, a 1-butenyl group, a cinnamyl group, and a 2-chloro-l-ethenyl group; and examples of the alkynyl group include an ethynyl group, a 1-propynyl group, a 1-butynyl group, and a trimethylsilylethynyl group.
• G1 in the acyl group (G1CO-) hydrogen and the foregoing alkyl group and aryl group can be enumerated.
• a halogen atom for example, -F, -Br, -Cl, and -I
• an alkoxy group for example, -F, -Br, -Cl, and -I
• an alkoxy group for example, -F, -Br, -Cl, and -I
• an alkoxy group for example, -F, -Br, -Cl, and -I
• an alkoxy group for example, -F, -Br, -Cl, and -I
• an alkoxy group for example, -F, -Br, -Cl, and -I
• an alkoxy group for example, -F, -Br, -Cl, and -I
• an alkoxy group for example, -F, -Br, -Cl, and -I
• an alkoxy group for example, -F, -Br, -Cl, and -I
• alkylene group on the substituted alkyl group there are enumerated divalent organic residues resulting from elimination of any one of hydrogen atoms on the foregoing alkyl group having from 1 to 20 carbon atoms.
• linear alkylene groups having from 1 to 12 carbon atoms, branched alkylene groups having from 3 to 12 carbon atoms, and cyclic alkylene groups having from 5 to 10 carbon atoms are preferable.
• Specific examples of the preferred substituted alkyl group as R 1 , R 2 , and R 3 as obtained by combining the subject substituent with the alkylene group include a chloromethyl group, a bromomethyl group, a 2-chloroethyl group, a trifluoromethyl group, a methoxymethyl group, a methoxyethoxyethyl group, an allyloxymethyl group, a phenoxymethyl group, a methylthiomethyl group, a tolylthiomethyl group, an ethylaminoethyl group, a diethylaminopropyl group, a morpholinopropyl group, an acetyloxymethyl group, a benzoyloxymethyl group, an N-cyclohexylcarbamoyloxyethyl group, an N-phenylcarbamoyloxyethyl group, an acetylaminoethyl group, an N-methylbenzoylamin
• aryl group which is preferred as R 1 , R 2 , and R 3 include ones resulting from the formation of a fused ring of from one to three benzene rings and ones resulting from the formation of a fused ring of a benzene ring and a 5-membered unsaturated ring.
• Specific examples thereof include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, an indenyl group, an acenaphthenyl group, and a fluorenyl group. Of these, a phenyl group and a naphthyl group are more preferable.
• substituted aryl group which is preferred as R 1 , R 2 , and R 3 include ones having a monovalent non-metallic atomic group other than hydrogen as the substituent on the ring-forming carbon atoms of the foregoing aryl group.
• preferred substituent include the foregoing alkyl groups and substituted alkyl groups and those as enumerated as the substituent in the foregoing substituted alkyl group.
• Preferred examples of such substituted aryl groups include a biphenyl group, a tolyl group, a xylyl group, a mesityl group, a cumenyl group, a chlorophenyl group, a bromophenyl group, a fluorophenyl group, a chloromethylphenyl group, a trifluoromethylphenyl group, a hydroxyphenyl group, a methoxyphenyl group, a methoxyethoxyphenyl group, an allyloxyphenyl group, a phenoxyphenyl group, a methylthiophenyl group, a tolylthiophenyl group, an ethylaminophenyl group, a diethylalninophenyl group, a morpholinophenyl group, an acetyloxyphenyl group, a benzoyloxyphenyl group, an N-cyclohexylcarbamo
• a in the formula (1) represents an optionally substituted aromatic ring or hetero ring.
• the optionally substituted aromatic ring or hetero ring those which are the same described above for R 1 , R 2 , and R 3 in the formula (1) are enumerated.
• the sensitizing dye represented by the formula (1) according to the invention is obtained by condensation reaction between the foregoing acidic nucleus or active methylene group-containing acidic nucleus and a substituted or unsubstituted aromatic ring or hetero ring and can be synthesized while referring to JP-B-59-28329.
• the photosensitive layer to be formed on the support must have an absorbance (Abs) of an emitting wavelength of laser for exposure of not more than 0.4.
• the subject absorbance exceeds 0.4, the light absorption distribution to the film thickness direction of the photosensitive layer inclines toward the surface of the photosensitive layer and uniform light absorption and polymerization to the film thickness direction do not proceed to the vicinity of the surface of the support so that a uniform hardened film is not obtained and that printing resistance and reproducibility of small dots are deteriorated. Therefore, such is not preferable.
• the subject absorbance is preferably in the range of from 0.05 to 0.4, more preferably in the range of from 0.1 to 0.3, and further preferably in the range of from 0.1 to 0.25.
• the subject absorbance can be regulated by the amount of addition of the foregoing sensitizing dye.
• the amount of addition of the sensitizing dye may be properly regulated depending upon the structure thereof.
• the sensitizing dye is used in an amount ranging from 1.0 to 10.0 % by weight of the whole of components of the photosensitive layer.
• polymerization initiator which is contained in the photosensitive layer to be used in the invention
• a variety of polymerization initiators which are known in patents, documents, and the like, or a combined system (photopolymerization initiation system) of two or more kinds of polymerization initiators can be properly chosen and used.
• the polymerization initiator which is used singly and the combined system of two or more kinds of polymerization initiators are collectively referred to simply as "polymerization initiator".
• benzil benzoin ether, Michler's ketone, anthraquinone, thioxanthone, acridine, phenazine, benzophenone, lophine dimer, and the like are widely used.
• photopolymerization initiators include certain kinds of photoreducible dyes, for example, Rose Bengale, eosine, and erythrosine, as described in U.S. Patent No.
• a combination of a dye and a photopolymerization initiator for example, a composite initiation system of a dye and an amine (as described in JP-B-44-20189), a combined system of a hexaaryl biimidazole, a radical generator and a dye (as described in JP-B-45-37377), a system of a hexaaryl biimidazole and a p-dialkylaminobenzylidene ketone (as described in JP-B-47-2528 and JP-A-54-155292), a system of a cyclic cis- ⁇ -dicarbonyl compound and a dye (as described in JP-A-48-84183) a system of a cyclic triazine and a merocyanine dye (as described in JP-A.-54-151024) , a system of 3-ketocourmarin and an activator (
• Patent No. 4,766,055 a system of a dye and an active halogen compound (as described in JP-A-63-178105, JP-A-63-258903, and JP-A-2-63054), a system of a dye and a borate compound (as described in JP-A-62-143044, JP-A-62-150242, JP-A-64-13140, JP-A-64-13141, JP-A-64-13142, JP-A-64-13143, JP-A-64-13144, JP-A-64-17048, JP-A-1-229003, JP-A-1-298348, and JP-A-1-138204), and a system of a rhodanine ring-containing dye and a radical generator (as described in JP-2-179643 and JP-A-2-249050).
• titanocene compounds are preferable as the polymerization initiator.
• the titanocene compound for example, known compounds as described in JP-A-59-152396 and JP-A-61-151197 can be properly chosen and used.
• dicyclopentadienyl-Ti-dihcloride dicyclopentadienyl-Ti-bisphenyl, dicyclopentadienyl-Ti-bis-2,3,4,5,6-pentafluorophen-1-yl, dicyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, dicyclopentadienyl-Ti-bis-2,4,6-trifluorophen-1-yl, dicyclopentadianyl-Ti-bis-2,6-difluorophen-1-yl, dicyclopentadienyl-Ti-bis-2,4-difluorophen-1-yl, dimethylcyclopentadienyl-Ti-bis-2,3,4,5,6-pentafluorophen-1-yl, dimethylcyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen
• the polymerization initiator is preferably used in an amount in the range of from 0.5 to 10.0 % by weight of the whole of components of the photosensitive layer. More preferably, the amount of the polymerization initiator is in the range of from 1.0 to 5.0 % by weight.
• the ethylenically unsaturated double bond-containing addition polymerizable compound which is contained in the photosensitive layer to be used in the invention can be arbitrarily chosen among compounds having at least one, and preferably two or more ethylenically unsaturated double bond groups.
• such a compound has a chemical morphology such as monomers and prepolymers, namely dimers, trimers and oligomers, or mixtures thereof, and copolymers thereof.
• Examples of monomers and copolymers thereof include esters of an unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, and maleic acid) and an aliphatic polyhydric alcohol compound and amides of an unsaturated carboxylic acid and an aliphatic polyhydric amine compound.
• esters of an unsaturated carboxylic acids for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, and maleic acid
• an aliphatic polyhydric alcohol compound and amides of an unsaturated carboxylic acid and an aliphatic polyhydric amine compound for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, and maleic acid
• acrylic esters include ethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butanediol diaCrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri(acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol diacrylate, tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol pent
• methacrylic esters examples include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimetharylate, 1,3-butanediol dimethacrylate, hexanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate, dipentaerythritol pentamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis[p-(3-methacryloxy-2-hydroxypropoxy)
• esters examples include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate, and sorbitol tetraitaconate.
• crotonic esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate.
• isocrotonic esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate.
• maleic esters examples include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate.
• specific examples of the monomer of the amide between an aliphatic polyhydric amine compound and an unsaturated carboxylic acid include methylene bisacrylamide, methylene bismethacrylamide, 1,6-hexamethylene bisacrylamide, 1,6-hexamethylene bismethacrylamide, diethylenetriamine trisaarylamide, xylylene bisacrylamdie, and xylylene bismethacrylamide.
• urethane acrylates as described in JP-A-51-37193; polyester acrylates as described in JP-A-48-64183, JP-B-49-43191, and JP-B-52-30490; and polyfunctional acrylates or methacrylates such as epoxy acrylates obtained by reaction between an epoxy resin and (meth)acrylic acid can be enumerated.
• Photocurable monomers and oligomers as introduced in Journal of the Adhesion Society of Japan, vol. 20, No. 7, pages 300 to 308 (1984) can also be used.
• the amount of the ethylenically unsaturated double bond-containing addition polymerizable compound to be used is preferably in the range of from 5 to 90 % by weight, and more preferably in the range of from 10 to 80 % by weight of the whole of components of the photosensitive layer.
• the binder polymer is not only used as a film forming agent of the photosensitive layer but also dissolved in an alkaline developing solution, organic high-molecular polymers which are soluble or swelling in alkaline water are used.
• organic high-molecular polymer a variety of materials can be enumerated.
• a water-soluble organic high-molecular polymer is used.
• organic high-molecular polymer include addition polymers having a carboxyl group in the side chain thereof, for example, ones as described in JP-A-59-44615, JP-B-54-34327, JP-B-58-12577, JP-B-54-25957, JP-A-54-92723, JP-A-59-53836, and JP-A-59-71048, namely methacrylic acid copolymers, acrylic acid copolymers, itaconic acid copolymers, crotonic acid copolymers, maleic acid copolymers, partially esterified maleic acid copolymers, and the like; acidic cellulose derivatives having a carboxyl group in the side chain thereof; ones obtained by adding a cyclic acid anhydride to an addition polymer
• copolymers of [benzyl (meth)acrylate/ (meth) acrylic acid/optionally other addition polymerizable vinyl monomer] and copolymers of [allyl (meth)-acrylate/(meth)acrylic acid/optionally other addition polymerizable vinyl monomer] are especially preferable.
• polyurethane resins as described in JP-B-7-120040, JP-B-7-120041, JP-B-7-120042, JP-B-8-12424, JP-A-63-287944, JP-A-63-287947, JP-A-1-271741, and JP-A-11-352691 can be used for the applications of the invention.
• a radical reactive group in such a high-molecular polymer, by introducing a radical reactive group into the side chain thereof, it is possible to enhance the strength of a hardened film.
• a functional group which can undergo addition polymerization reaction include an ethylenically unsaturated bond group, an amino group, and an epoxy group.
• examples of a functional group which can become a radical upon irradiation with light include a mercapto group, a thiol group, a halogen atom, a triazine structure, and an onium salt structure; and examples of a polar group include a carboxyl group and an imido group.
• ethylenically unsaturated bond groups such as an acryl group, a methacryl group, an allyl group, and a styryl group are especially preferable
• a functional group selected from an amino group, a hydroxyl group, a phosphonic acid group, a phosphoric acid group, a carbamoyl group, an isocyanate group, an ureido group, an ureylene group, a sulfonic acid group, and an ammonio group can also be used.
• binder polymer which is suitable in the invention, ones having at least structural units represented by the following formulae (1) to (3) are desirable.
• R 1 , R 2 , and R 3 each independently represents a hydrogen atom or an alkyl group having from 1 to 6 carbon atoms;
• X represents a functional group selected from -COOH, -CO-W 1 -L 1 -COOH, and -SO 3 H;
• W 1 represents an oxygen atom, a sulfur atom, or an -NH- group;
• L 1 represents a divalent organic group;
• W 2 represents an oxygen atom, a sulfur atom, or an -NH- group;
• L 2 represents a divalent organic group;
• R 4 represents a hydrogen atom or an alkyl group having from 1 to 6 carbon atoms;
• W 3 represents an oxygen atom, a sulfur atom, or an -NH- group;
• R 5 represents an alkyl group having
• a monomer which can form the structural unit of the formula (3) include alkyl or aryl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)-acrylate, isobutyl (meth)acrylate, n-butyl (meth) acrylate, isopropyl (meth) acrylate, cycloheacyl (math) acrylate, n-hexyl (meth) acrylate, adamantyl (meth)acrylate, benzyl (meth)-acrylate, and phenethyl (meth)acrylate.
• alkyl or aryl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)-acrylate, isobutyl (meth)acrylate, n-butyl (meth) acrylate, isopropyl (meth) acrylate, cycloheacyl (math) acrylate, n-
• the binder polymer to be used in the invention has suitable molecular weight and acid value.
• a binder polymer having a weight average molecular weight of from 5,000 to 300,000 and an acid value of from 0.5 to 200 is especially preferable.
• the proportion of the structural units represented by the formulae (1), (2) and (3) is useful so far as it satisfies the requirements of the foregoing molecular weight, acid value and amount of a double bond.
• the amount of (1) is in the range of from 1 to 70 % by weight
• that of (2) is in the range of from 0.5 to 98 % by weight
• that of (3) is in the range of from 0.5 to 98 % by weight in terms of a weight ratio.
• the amount of the binder polymer to be contained is preferably from 10 to 90 % by weight, and more preferably from 30 to 80 % by weight.
• a proportion of the foregoing ethylenically unsaturated double bond-containing addition polymerizable compound and the binder polymer to be used is not more than 1.5, especially from 0.1 to 1.5, preferably from 0.1 to 1.0, and more preferably from 0.1 to 0.8 in terms of a weight ratio of the former to the latter.
• binder polymers than the foregoing binder polymers can be mixed and used.
• organic high-molecular polymers a variety of materials can be enumerated. When water development is desired, for example, a water-soluble organic high-molecular polymer is used.
• organic high-molecular polymer include addition polymers having a carboxyl group in the side chain thereof, for example, ones as described in JP-A-59-44615, JP-B-54-34327, JP-B-58-12577, JP-B-54-25957, JP-A-54-92723, JP-A-59-53836, and JP-A-59-71048, namely methacrylic acid copolymers, acrylic acid copolymers, itaconic acid copolymers, crotonic acid copolymers, maleic acid copolymers, partially esterified maleic acid copolymers, and the like; acidic cellulose derivatives having a carboxyl group in the side chain thereof; ones obtained by adding a cyclic acid anhydride to an addition polymer having
• polyurethane resins as described in JP-B-7-120040, JP-B-7-120041, JP-B-7-120042, JP-B-8-12424, JP-A-63-287944, JP-A-63-287947, JP-A-1-271741, and JP-A-11-352691 can be used for the applications of the invention.
• the photosensitive layer to be used in the invention in addition to the foregoing basic components, it is desired to add a small amount of a thermal polymerization inhibitor during the production or storage of the composition (photosensitive composition) for forming a photosensitive layer for the purpose of preventing unnecessary thermal polymerization of the ethylenically unsaturated double bond-containing addition polymerizable compound from occurring.
• thermal polymerization inhibitor examples include hydroquinone, p-methoxyphenol, di-t-butyl-p-oresol, pyrogallol, t-butyl chatecol, benzoquinone, 4,4'-thiobis(3-methyl-6-t-butylphenol), 2,2'-methylenebis-(4-methyl-6-t-butylphenol), N-nitrosophenylhydroxylamine cerous salt, and N-nitrosophenylhydroxylamine aluminum salt.
• the amount of addition of the thermal polymerization inhibitor is preferably from about 0.01 % by weight to about 5 % by weight of the whole of components of the foregoing composition.
• a higher fatty acid derivative such as behenic acid and behenic amide may be added, thereby unevenly distributing it on the surface of the photosensitive layer during a drying step to be carried out after coating.
• the amount of addition of the higher fatty acid derivative is preferably from about 0.5 % by weight to about 10 % by weight of the whole of components of the photosensitive composition.
• a coloring agent may be added for the purpose of coloring the photosensitive layer.
• the coloring agent include pigments (for example, phthalocyanine based pigments (for example, C.I. Pigment Blue 15:3, C.I. Pigment Blue 15:4, and C.I. Pigment Blue 15:6), azo based pigments, carbon black, and titanium oxide) and dyes (for example, Ethyl Violet, Crystal Violet, azo dyes, anthraquinone based dyes, and cyanine based dyes).
• the amount of addition of the dye or pigment is preferably from about 0.5% by weight to about 5 % by weight of the whole of components of the photosensitive composition.
• additives such as inorganic fillers and plasticizers (for example, dioctyl phthalate, dimethyl phthalate, and tricresyl phosphate) may be added.
• the amount of addition of such an additive is preferably not more than 10 % by weight of the whole of components of the photosensitive composition.
• a surfactant in the composition for forming the photosensitive layer.
• a surfactant for example, fluorine based nonionic surfactants can be enumerated.
• the photosensitive composition is coated on the foregoing support which has been optionally subjected to every kind of surface treatment.
• the photosensitive composition In coating the photosensitive composition on the support, it is dissolved in every kind of an organic solvent and then provided for use.
• the solvent which can be used herein include acetone, methyl ethyl ketone, cyclohexane, ethyl acetate, ethylene dichloride, tetrahydrofuran, toluene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, acetylacetone, cyclohexanone, diacetone alcohol, ethylene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether acetate, 3-meth
• the amount of coating of the photosensitive layer which is used in the invention is suitably in the range of from about 0.5 g/m 2 to 3.0 g / m 2 , more preferably from 9.7 g/m 2 to 2.5 g/m 2 , and further preferably from 0.8 g/m 2 to 2.0 g/m 2 in terms of a weight after coating and drying.
• an oxygen-blocking protective layer (overcoat layer) is usually provided on the foregoing photosensitive layer for the purpose of preventing a polymerization inhibiting action of oxygen.
• the weight of coating of the protective layer is preferably in the range of from 0.7 to 3.0 g/m 2 .
• Examples of a water-soluble vinyl polymer which is contained in the oxygen-blocking protective layer include polyvinyl alcohol and its partial esters, ethers and acetals, and copolymers thereof containing a substantial amount of an unsubstituted vinyl alcohol unit so as to imparting necessary water solubility.
• polyvinyl alcohol there are enumerated polyvinyl alcohols which are hydrolyzed to an extent of from 71 to 100 % and which have a molecular weight in the range of from 300 to 2,400.
• PVA-105 PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA-124H, PVA-CS, PVA-CST, PVA-HC, PVA-203, PVA-204, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-224E, PVA-405, PVA-420, PVA-613, and L-8, all of which are manufactured by Kuraray Co., Ltd.
• copolymer examples include polyvinyl acetate chloroacetate or propionate, polyvinyl formal and polyvinyl acetal, each of which is hydrolyzed to an extent of from 88 to 100 %, and copolymers thereof.
• polyvinylpyrrolidone examples include polyvinylpyrrolidone, gelatin, and gum arabic. These polymers may be used singly or in combination.
• pure water is preferable as a solvent to be used in coating the oxygen-blocking protective layer in the photosensitive lithographic printing plate in the invention
• an alcohol for example, methanol and ethanol
• a ketone for example, acetone and methyl ethyl ketone
• a concentration of solids in the coating solution is suitably from 1 to 20 % by weight.
• known additives such as a surfactant for further enhancing coating properties and a water-soluble plasticizer for improving physical properties of the film may be added.
• the water-soluble plasticizer include propionamide, cyclohexanediol, glycerin, and sorbitol.
• a water-soluble (meth) acrylate based polymer or the like may be added.
• the amount of coating thereof is suitably in the range of from about 0.1 g/m 2 to about 15 g/m 2 in terms of a weight after drying. It is more preferably from about 1.0 g/m 2 to about 5.0 g/m 2 .
• an AlGaInN semidonductor laser (commercially available InGaN based semiconductor lasers: 5 to 30 mW) is suitable as a light source in view of wavelength characteristics and costs.
• any of an internal drum system, an external drum system, a flat bed system, and so on may be employed.
• a highly water-soluble material as the photosensitive layer component of the photosensitive lithographic printing plate of the invention, it is possible to make the material soluble in neutral water or weakly alkaline water.
• a system in which after mounting a photosensitive lithographic printing plate having such a construction on a printing machine, exposure and development are carried out on the machine. After the image exposure, if desired, the entire surface may be heated during a period of from exposure to development.
• the image after development is also effective to subject, the image after development to entire post-heating or entire exposure.
• heating before the development is carried out under a mild condition of not higher than 150 °C.
• a very strong condition is applied.
• the heating after the development is carried out at a temperature in the range of from 200 to 500 °C.
• the developing solution which is used in the foregoing plate-making process of the lithographic printing plate is not particularly limited.
• a developing solution containing an inorganic alkaline salt and a nonionic surfactant and having a pH of not more than 13 is suitably used.
• the pH of the developing solution is more preferably from 12.5 to 10.0.
• the inorganic alkaline salt can be properly used.
• examples thereof include inorganic alkaline agents such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, lithium hydroxide, sodium silicate, potassium silicate, ammonium silicate, lithium silicate, sodium triphosphate, potassium triphosphate, ammonium triphosphate, sodium carbonate, potassium carbonate, ammonium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate, ammonium hydrogencarbonate, sodium borate, potassium borate, and ammonium borate.
• These inorganic alkaline agents may be used singly or in combination of two or more kinds thereof.
• a silicate In the case where a silicate is used, it is possible to easily regulate developability by regulating a mixing ratio and concentration of silicon oxide SiO 2 as a component of the silicate and an alkaline oxide M 2 O (wherein M represents an alkali metal or an ammonium group).
• M represents an alkali metal or an ammonium group.
• a mixing ratio of the foregoing silicon oxide SiO 2 and the alkaline oxide M 2 O a molar ratio of SiO 2 /M 2 O
• ones having the subject mixing ratio of from 1.0 to 2.0 are more preferable.
• the concentration of the silicate is preferably from 1 to 10 % by weight, more preferably from 3 to 8 % by weight, and most preferably from 4 to 7 % by weight based on the weight of the alkaline aqueous solution.
• this concentration is 1% by weight or more, the developability and treatment ability are not lowered; and when it is not more than 10 % by weight, precipitation or crystallization hardly occurs, and gelation hardly occurs during neutralization at the time of discharging a waste liquid so that the treatment of waste liquid is not impaired.
• an organic alkaline agent may be auxiliarily used jointly.
• the organic alkaline agent which can be used include monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, ethyleneimine, ethylenediamine, pyridine, and tetramethylammonium hydroxide.
• These alkaline agents are used singly or in combination of two or more kinds thereof.
• the surfactant can be properly used.
• nonionic surfactants such as polyoxyalkylene ether group-containing nonionic surfactants, polyoxyethylene alkyl esters (for example, polyoxyethylene stearate), sorbitan alkyl esters (for example, sorbitan monolaurate, sorbitan monostearate, sorbitan distearate, sorbitan monooleate, sorbitan sesquioleate, and sorbitan trioleate), and monoglyceride alkyl esters (for example, glycerol monostearate and glycerol monooleate) ; anionic surfactants such as alkylbenzenesulfonic acid salts (for example, sodium dodecylbenzenesulfonate), alkylnaphthalenesulfonic acid salts (for example, sodium butylnaphthalenesulfonate, sodium pentylnaphthalenesulfonate, sodium hex
• polyoxyalkylene ether group-containing nonionic surfactant ones having a structure represented by the following formula (I) are suitably used.
• R 40 represents an optionally substituted alkyl group having from 3 to 15 carbon atoms, an optionally substituted aromatic hydrocarbon group having from 6 to 15 carbon atoms, or an optionally substituted heteroaromatic ring group having from 4 to 15 carbon atoms
• substituents include an alkyl group having from 1 to 20 carbon atoms, a halogen atom (for example, Br, Cl, and I), an aromatic hydrocarbon group having from 6 to 15 carbon atoms, an aralkyl group having from 7 to 17 carbon atoms, an alkoxy group having from 1 to 20 carbon atoms, an alkoxycarbonyl group having from 2 to 20 carbon atoms, and an acyl group having from 2 to 15 carbon atoms);
• R 41 represents an optionally substituted alkylene group having from 1 to 100 carbon atoms
• substituent include an alkyl group having from 1 to 20 carbon atoms and an aromatic hydrocarbon group having from
• aromatic hydrocarbon group examples include a phenyl group, a tolyl group, a naphthyl group, an anthryl group, a biphenyl group, and a phenanthryl group; and specific examples of the "heteroaromatic ring group” include a furyl group, a thienyl group, an oxazolyl group, an imidazolyl group, a pyranyl group, a pyridinyl group, an acridinyl group, a benzofuranyl group, a benzothienyl group, a benzopyranyl group, a benzoxazolyl group, and a benzimidazolyl group.
• the (R 41 -0) p moiety of the formula (I) may be a combination of two or three kinds of groups so far as it falls within the foregoing range.
• the polyoxyalkylene ether group-containing surfactant is used singly or in a composite system. It is effective to add the polyoxyalkylene ether group-containing surfactant in an amount of from 1 to 30 % by weight, and preferably from 2 to 20 % by weight in the developing solution in view of developability and printing resistance of a printing plate.
• examples of the polyoxyalkylene ether group-containing nonionic surface represented by the foregoing formula (I) include polyoxyethylene alkyl ethers (for example, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, and polyoxyethylene stearyl ether), polyoxyethylene aryl ethers (for example, polyoxyethylene phenyl ether and polyoxyethylene naphthyl ether), and polyoxyethylene alkylaryl ethers (for example, polyoxyethylene methylphenyl ether, polyoxyethylene octylphenyl ether, and polyoxyethylene nonylphenyl ether).
• polyoxyethylene alkyl ethers for example, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, and polyoxyethylene stearyl ether
• polyoxyethylene aryl ethers for example, polyoxyethylene phenyl ether and polyoxyethylene naphthyl ether
• polyoxyethylene alkylaryl ethers for example, polyoxyethylene methyl
• Such a surfactant can be used singly or in combination. Furthermore, the content of such a surfactant in the developing solution is suitably in the range of from 0.1 to 20 % by weight as reduced into an active ingredient.
• the subject developing solution has a conductivity of from 3 to 30 mS/cm.
• the conductivity is 3 mS/cm or more, elution of the photopolymerizable photosensitive layer on the surface of the aluminum support becomes surely possible so that staining is not caused during printing.
• the conductivity is not more than 30 mS/cm, since the salt concentration does not become excessively high, an elution rate of the photopolymerizable photosensitive layer does not become extremely low, and a residual film is not generated in an unexposed area.
• the conductivity is especially preferably in the range of from 5 to 20 mS/cm.
• the development of the photosensitive lithographic printing plate is carried out at a temperature of from about 0 to 60 °C, and preferably from about 15 to 40 °C according to a conventional method by, for example, dipping the exposed photosensitive lithographic printing plate in a developing solution and rubbing it with a brush or other means.
• the thus developed photosensitive lithographic printing plate is subjected to post treatments with washing water, a rinse liquid containing a surfactant, etc., and a desensitizing liquid containing gum arabic, a starch derivative, etc. as described in JP-A-54-8002, JP-A-55-115045, JP-A-59-58431, and the like.
• a combination of a variety of these treatments can be employed for the post treatments of the photosensitive lithographic printing plate.
• the lithographic printing plate as obtained by these treatments is set in an offset printing machine and provided for printing of a number of sheets.
• the surface of an aluminum plate (material quality: 1S) having a thickness of 0.30 mm was subjected to graining by using a No. 8 nylon brush and an aqueous suspension of 800-mesh pamiston and then thoroughly washed with water.
• the resulting aluminum plate was dipped in and etched with 10 % by weight sodium hydroxide at 70 °C for 60 seconds, washed with running water, neutralized and washed with 20 % by weight HNO 3 , and then washed with water.
• the aluminum plate was subjected to electrolytic roughing treatment in a quantity of electricity at the time of anode of 300 coulombs/dm 2 in a 1 % by weight nitric acid aqueous solution using an alternating waveform current of sine wave under a condition at a VA of 12.7 V. A surface roughness thereof was measured and found to be 0.45 ⁇ m (in terms of an Ra expression) .
• the resulting aluminum plate was dipped in a 30 % H 2 SO 4 aqueous solution, subjected to desmutting at 55 °C for 2 minutes, and then subjected to anodic oxidation in a 20 % H 2 SO 4 aqueous solution at a current density of 5 A/dm 2 for 50 seconds while disposing an anode on the grained surface.
• an anodically oxidized film had a thickness of 2.6 g/m 2 .
• This support was designated as "support 1".
• the following polymer (P1) solution was coated in the amount of coating after drying of 2 mg/m 2 on the foregoing support (1) by using a bar coater, followed by drying at 80 °C for 20 seconds.
• a photosensitive composition (1) having the following composition was coated on this support (2) by using a bar coater, followed by drying at 100°C for one minute.
• the weight of the photosensitive composition after drying was 1.1 g/m 2 .
• Sensitizing dye Parts by weight as des cribed in Table 1
• Polymerization initiator (C-1) 0.14 parts by weight ⁇ -Phthalocyanine (F-1) dispersion: 1.7 parts by weight
• Sensitizing assistant G-1): 0.5 parts by weight Fluorine based nonionic surfactant MEGAFAC F-78OF (manufactured by Dainippon Ink and Chemicals, Incorporated) 0.03 parts by weight
• Methyl ethyl ketone 27.0 parts by weight
• Propylene glycol monomethyl ether 26.7 parts by weight
• the ethylenically unsaturated bond-containing compound (A-1), high-molecular binder (B-1), photopolymerization initiator (C-1), ⁇ -phthalocyanine (F-1) and sensitizing assistant (G-1) as used for the preparation of the photopolymerizable photosensitive compositions of the present Examples and the following Comparative Example were compounds having the following chemical formulae, respectively.
• the sensitizing dye D10 or D30 as enumerated in the foregoing specific examples was used.
• aqueous solution for protective layer was coated in the amount of coating after drying of 2.5 g/m 2 on this photosensitive layer by using a bar coater, followed by drying at 120 °C for one minute. There were thus obtained photosensitive lithographic printing plates 1 to 2.
• (Aqueous solution for protective layer) Polyvinyl alcohol (degree of hydrolysis: 98 % by mole, degree of polymerization: 500) : 5.0 parts by weight EMALEX 710 (nonionic surfactant as manufactured by Nippon Nyukazai Co., Ltd.) : 0.09 parts by weight Pure water: 94.91 parts by weight
• Each of the foregoing polymerizable photosensitive compositions P-1 to P-2 was coated on a glass support such that the amount of coating after drying was the same as in the photosensitive layer of the photosensitive lithographic printing plate, and its transmitted UV spectrum was measured by using a spectrophotometer (U3000 as manufactured by Hitachi, Ltd.) as a measurement analyzer, thereby measuring an absorbance at 405 nm which is an emitting wavelength of a laser to be used herein. The results obtained are shown in Table 1.
• Each of the foregoing photosensitive lithographic printing plate precursors was mounted on a violet semiconductor laser setter VX9600 as manufactured by FUJIFILM Electronic Imaging Ltd. (InGaN based semiconductor laser, 405 nm ⁇ 10 nm, emission/output: 30 mW) and subjected to image drawing with a flat tint of 35 % at an exposure amount of 90 ⁇ J/cm 2 and at a resolution of 2,438 dpi by using an FM screen TAFFETA 20 as manufactured by Fuji Photo Film Co., Ltd.
• the plate after the exposure was automatically sent to an automatic processor LP1250 PLX (equipped with a brush) as connected thereto, thermally treated at 100 °C for 10 seconds, and after removing the PVA protective layer by water washing, developed at 28 °C for 20 seconds.
• a developing solution one obtained by diluting a developing solution DV-2 as manufactured by Fuji Photo Film Co., Ltd. with water at a dilution of 5 times.
• the developed plate was water washed in a rinse bath and then sent to a gumming bath.
• As the gumming bath one obtained by diluting a gum liquid EP-2W as manufactured by Fuji Photo Film Co., Ltd. with water at a dilution of 2 times.
• the gummed plate was dried by hot air and then discharged to obtain a lithographic printing plate having been subjected to image drawing with a flat tint.
• a rate of area of the flat tint of the resulting lithographic printing plate was measured by using CC-dot, thereby measuring a difference of area ( ⁇ dot) between the maximum and the minimum. The results obtained are shown in Table 1.
• a photosensitive composition P-3 was prepared in the same manner as in the Examples, except for changing the amount of addition of the sensitizing dye in the foregoing Examples to one as described in Table 1. Using a photopolymerizable photosensitive lithographic printing plate having a photosensitive layer of this photosensitive composition, a line width and a ⁇ dot were measured in the same manner as in the Examples. The results obtained are shown in Table 1.

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